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Transition to Unleaded Avgas — What Does the Future Hold, How Much Work Remains?

Refueling Plane

On September 1, the FAA issued an Approved Model List Supplemental Type Certificate (AML STC) to General Aviation Modifications Inc. (GAMI) for their G100UL unleaded avgas. It represents the first FAA approval of a high-octane unleaded fuel for general aviation aircraft and moves the industry a step closer to an unleaded future. GAMI’s STC opens the door to the complex work that remains to create a commercial pathway for this, and other unleaded fuels under development, to reach the marketplace and become available for purchase.

On the heels of this announcement, many are asking what the path to an unleaded future looks like. Questions concerning proposed high-octane unleaded fuels involve availability, production and distribution, operational differences or limitations, and price. In the meantime, concern over the continued availability of 100LL and its likely future phase-out persist.

Meanwhile, the Environmental Protection Agency (EPA) is in the final stages of coordinating a draft endangerment finding for lead emissions from piston aircraft. This is the first of multiple regulatory steps that will unfold over the coming years that will likely lead to an EPA emissions standard for lead from aircraft and FAA regulation that eventually phases out the use of leaded.

GAMI’s Path to Deployment

GAMI has announced that they are collaborating with Avfuel Corporation, utilizing their logistics and distribution experience, to develop a network needed to facilitate the fuel’s distribution. According to early communications by GAMI and Avfuel, “G100UL avgas will expand nationally over a period of a few years at a pace driven by the rate at which the production and distribution infrastructure can be put in place.” Regarding production, GAMI states, “Our arrangement is that any qualified refiner or blender of existing aviation fuels will be eligible to produce and sell it subject to the quality assurance requirements that the FAA has approved.” So, progress in the production and distribution of the GAMI fuel will depend upon agreements the company reaches with fuel refiners, distributors, and others. These will be business decisions by all of the involved stakeholders.

Price is yet to be determined but will likely be more than avgas. When discussing the price of G100UL, GAMI estimates that their fuel will cost more than 100LL, but the gap could close as production increases and the market adapts. This price difference will be a critical consideration for pilots and aircraft owners where G100UL and 100LL compete in the same market. GAMI notes that this price differential could be offset by the reduced maintenance costs associated with burning an unleaded fuel.

In addition to fuel production and distribution matters, aircraft and engine manufacturers will be seeking information and data necessary to satisfy their own business, liability, and product support considerations. It is anticipated that some will want to evaluate and test the fuel themselves as part of reaching their conclusions. All of this leads to the understanding that evaluation, production, and broad distribution will take time and require business decisions by many stakeholders.

Additional Unleaded Fuel Candidates

In addition to GAMI, three other high-octane unleaded fuels are in development and are working toward FAA approval or authorization. Each of these fuels attempt to tackle the need for high-octane aviation fuel using differing chemical approaches. As with all unleaded fuel technologies explored to date, each has unique advantages and disadvantages relative to one another. In the end, it is in the best interest of the general aviation community to have more than one high-octane unleaded fuel gain FAA approval and compete for the market based upon technical, safety, production, and economic merits.

Swift Fuels Inc., an Indiana-based company, already supplies its 94-octane unleaded fuel to a limited but growing number of airports for those aircraft that can use a lower octane fuel and hold an STC for the fuel. The company is currently working through the FAA STC approval process on its 100-octane unleaded avgas product and has said that it hopes to have a fleet solution ready to deploy for North America by the end of 2024.

Partnerships between Afton Chemical/Phillips 66 and Lyondell/VP Racing have each developed high-octane fuels as potential replacements for 100LL. Rather than seeking STC approval from the FAA, both of these partnerships participate in the Eliminate Aviation Gasoline Lead Emissions (EAGLE) program for the evaluation and eventual authorization of their fuels. EAGLE is a government-industry partnership that brings together aircraft and engine manufacturers, fuel producers and distributors, airport operators, communities supporting general aviation airports, and environmental experts with the goal of transitioning to lead-free aviation fuels for piston-engine aircraft by the end of 2030. EAGLE's work focuses on critical areas of activity necessary to protect the interests of general aviation while facilitating a safe transition to an unleaded replacement avgas without adversely affecting the existing piston-engine fleet. It also stands ready to assist companies who have sought FAA approval by way of the STC pathway to deploy their fuels into the marketplace.

Future of 100LL — EPA and Local Pressures

The EPA is in the final stages of coordinating a draft endangerment finding for lead emissions from piston aircraft that use leaded aviation gasoline. A proposed finding of endangerment is just the first of several regulatory steps that will be taken in the coming years that will most likely conclude with the eventual elimination of leaded avgas. In the meantime, as unleaded alternatives continue to be examined and their deployment carried out, EAA and the aviation industry are committed to ensuring the continued availability of 100LL throughout the transition to ensure safety and continued viability of the existing aircraft fleet.

The continued use of leaded avgas through the transition period will likely attract opposition and result in growing pressure on airports and operators at the state and local level. Most recently, California’s Santa Clara County has moved to ban the sale of leaded avgas at its two airports, Reid-Hillview Airport (RHV) and San Martin Airport (E16). A well-coordinated and communicated plan for transitioning to a high-octane unleaded avgas is what was needed and that is where EAGLE comes in. This collaborative effort bring all of the stakeholders in aviation, the petroleum industry, and government together to effect a timely, safe, and viable transition away from leaded aviation gasoline. A patchwork of airport-specific requirements leading to inconsistency in what fuels are available would lead to airports that may or may not carry the necessary fuels, thus creating a situation where aircraft could be misfueled, leading to safety and operational concerns.

EAA’s Continued Commitment

EAA is committed to facilitating a smart and safe transition to an unleaded fuel that preserves the utility of the existing general aviation fleet and provides a stable and cost-effective fuel supply now and into the future. The ongoing development and expansion of unleaded fuel availability is critical to the long-term success of general aviation.

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